Inductors capable of having their inductances adjusted



G. W- HENKE March 8, 1966 INDUCTORS CAPABLE OF HAVING THEIR INDUCTANGES ADJUSTED Filed Jan. 2, 1962 FIG. 5'

. FIG 3 FIG. 4-

FIG

FIG-2 FIG. 8 FIG. 9 FIG. /0

FIG. 7 FIG. 6

FIG/3 FIG. /2

Fl G. /5 INVENTOR.

GUST/IVE "f flfN/ff ATTORNEY United States Patent 3,239,782 INDUCTORS CAPABLE OF HAVING THEIR INDUCTANCES ADJUSTED Gustave W. Henlte, Freeport, N.Y., assignor, by mesne assignments, to Varian Associates, Palo Alto, Calif, a

corporation of California Filed Jan. 2, 1962, Ser. No. 163,936 14 Claims. (Cl. 336-73) This invention relates to continuously variable inductors and more specifically to those of miniature type which might also be encapsulated to exclude the effects of moisture and other effects.

One of the objects of the invention is to provide exact adjustment of inductance with minimum cost in construction and assembly.

A specific object of the invention is to improve over the prior methods of varying an inductance; these prior methods consist mainly of the insertion of a ferrous or non-ferrous metallic slug inside the windings of an inductance.

Another object of the invention is to provide a solenoid inductor of cylindrical external shape or any shape allowing for the placement of a screw thread coaxially with the winding of the inductance. A metallic nut or sleeve screwed over these threads will cause the inductance to decrease as the position of the nut moves to the center of the coil.

These and other objects of the invention will be more fully apparent from the drawings enclosed herewith in which FIG. 1, shows a miniature type of variable inductor.

FIG. 2 represents a corresponding circuit diagram.

FIGS. 3 and 4 show a modification of this embodiment in a more simple form not requiring the use of a screw thread.

FIG. 5 illustrates another modification of the invention involving a thread on insulating material.

FIG. 6 represents a variable inductor embodying the invention in the form of an auto-transformer.

FIG. 7 represents a corresponding circuit diagram.

FIG. 8 shows two inductors in accordance with the invention adjustable simultaneously.

FIG. 9 shows a variable inductor adjustable by means of a special tool which is illustrated in a side view shown in FIG. 10.

FIG. 11 shows the invention as applied to a radio frequency transformer.

FIG. 12 shows an adjustable miniature inductance in accordance with the invention permitting fixation of the adjustment.

FIG. 13 shows a modification of the embodiment shown in FIG. 12.

FIG. 14 shows a variable inductance in accordance with the invention in the form of a double tuned circuit, and FIG. 15 shows the corresponding circuit diagram.

In FIG. 1 a plastic or other insulating capsule 1 containing a coil not shown is provided at least at a portion thereof with a thread schematically indicated at 2 over which metal nut or ring 3 is adjustable to permit adjustment of the inductance in accordance with the equivalent circuit diagram of coil 4, shown in FIG. 2.

The actual size of such a miniature type variable inductance can be of the order of less than an inch, its length for example being half an inch and its outer diameter A; of an inch, while the metal ring 3 has an outer diameter of A of an inch. The terminal leads are indicated at 5, 6, respectively.

The modification of FIG. 3 shows in schematical form a coil capsule or cylinder 7 having axial end leads 8, 9 extending therefrom. Movable along the outside of cylinder 7 is a shorted turn of wire schematically indicated 3,239,782 Patented Mar. 8, 1966 at 10, permitting the inductance of the coil enclosed in 7 to be changed in a continuous movement.

As apparent from FIG. 3 shorting wire 10 is also connected to axial lead 8 by means of a wire 11 permitting to the adjustment of the inductor to be held at a fixed value, if desired.

FIG. 4 shows a metallic ring 12 provided with diagonal clips 13, 14, and arranged to be movable over the outer surface of capsule 15. In this way, threads on the capsule are not required.

According to FIG. 5, the inductor capsule 16 is provided with a sleeve of insulating material 17 which is arranged with push-fit over capsule 16, and which has an outer thread permitting adjustment of metal nut 18 over sleeve 17.

In the embodiment of FIG. 6, the inductor capsule 19 is provided with two axial end leads 20, 21 and a center tap lead 22 permitting it to act as an auto transformer with variable tap.

Adjustment of inductance is effected by nuts 23, 24 adjustable over corresponding threads, or thread portions of capsule 19.

The equivalent circuit diagram is indicated in FIG. 7.

FIG. 8 shows two inductor capsules 25, 26 arranged in parallel and provided with adjustment rings 27, 28 movable over outer threads under control over a common gear element schematically indicated at 29 and meshing with outer gears formed on nuts 27 and 28, respectively.

FIG. 9 shows the adjustment element or ring 30 movable over thread 31 of an inductor capsule under control of grooves 32 peripherally provided on the outside of nut 30. In the side elevation of FIG. 10, an adjusting tool 33 is indicated which has projections fitting into grooves 32 or nut 30 and permitting adjustment of inductance.

FIG. 11 illustrates the invention in the form of a radio frequency transformer.

The coil in the capsule of FIG. 11 consists of two separate windings, primary and secondary, indicated at 35, 36, respectively with corresponding terminal leads projecting at one end at 37, 38, 39, 40, respectively.

Adjustment nut 41 is movable over thread 42 to adjust or trim the inductance. If desired, windings 35, 36 may be provided instead of inside capsule 34, outside thereof, and of proper diameter and pitch to form a thread for direct application of adjustment nuts.

FIG. 12 shows an adjustment nut consisting of an inner core of insulating material schematically indicated at 43 which is pressed into a metallic outer ring or sleeve of metal schematically indicated at 44. The soft inner ring 43 is threaded over the thread provided on inductance capsule 45 to permit the soft material to hold adjustment.

In the arrangement of FIG. 13 metal nut or nuts schematically indicated at 46 are used to adjust the inductance capsule 47.

A nut of flexible material 48 may be used to hold metal nut 46 in adjustment.

Nut 48 may also be of metal to act as a lock nut, but it should be noted that additional metal nut or nuts decrease the inductance value.

It should also be noted that all rings, sleeves or nuts which are used for adjustment with respect to the inductor capsule may be covered with insulating material to prevent possible electrical contact and short circuit with other components or wiring.

FIG. 14 shows a variable inductor in the form of a double tuned circuit as illustrated in the equivalent circuit diagram of FIG. 15.

In this case, the inductor capsule schematically indicated at 49 contains three windings or coils schematically indicated at 50, 51 and 52 and extending into end leads or terminals 53, 54, and 55, respectively.

Capsule 49 is provided with an external screw thread 56 on which were arranged three nuts adjustable in accordance with the invention and schematically indicated at 57, 53, 59.

The invention is not limited to the particular shape of the inductor capsule nor to the arrangement and number of windings or coils shown and described nor to the particular circuit configuration and adjustment means which have been illustrated but may be applied in any form or manner whatsoever without departing from the scope of this disclosure.

I claim:

1. An inductor comprising a substantially cylindrical encapsulating means having opposite closed ends, at least one winding located in and extending axially of said encapsulating means, said winding having terminal leads projecting through at least one of said closed ends of said encapsulating means, said leads being the only elements which project from the interior of said encapsulating means outwardly through and beyond said closed ends thereof, and at least one metallic ring circumferentially surrounding said encapsulating means and said winding therein and being axially movable along said encapsulating means between said ends thereof, whereby said ring will also move axially of said winding for adjusting the inductance thereof, said ring constituting the only means by which said inductance can be adjusted.

2. Inductor according to claim 1, wherein said encapsulating means is provided with an outer thread and said ring is provided with a corresponding inner thread.

3. Inductor according to claim 1, wherein said ring is provided with outer recesses permitting gripping for peripheral adjustment.

4. Inductor according to claim 1, wherein said ring is provided with an outer gear permitting peripheral adjustment.

5. Inductor according to claim 1, wherein said encapsulating means contains secondary and primary windings arranged along its axis one after another and external terminals extending from the ends of the encapsulating means in the direction parallel to its axis.

6. Inductoraccording to claim 1, said terminal leads extending through said opposite closed ends along the axis of the encapsulating means.

7. Inductor according to claim 1, wherein said encapsulating means consists of insulating material.

8. Inductor according to claim 1, comprising a sleeve of insulating material fitted over the encapsulating means and provided with an outer thread, said ring consisting of a nut adjustable over said thread.

9. Inductor according to claim 1, comprising several windings connected in series arranged along the axis of said encapsulating means, one after another and having a center tap terminal extending to the outside, several rings being provided in the form of nuts adjustable over said windings to provide a variably tapped auto transformer.

10. Inductor according to claim 1, wherein the ring has an outer thread and means engaging said outer thread to provide adjustment.

11. Inductor according to claim 1, wherein said encapsulating means comprises at least two capsules each containing a single winding, and both having outer threads and arranged parallel, each being provided with a ring in the form of an adjustable nut having an outer thread and a common gear element driving said nuts at their outer threads for gang tuning.

12. Inductor according to claim 1, wherein said ring is grooved on its outside to permit adjustment by gripping.

13. Inductor according to claim 1, wherein said ring is in the form of a nut arranged at one end of the encapsulating means, and wherein said encapsulating means contain primary and secondary windings spaced along the axis of the capsule, with said terminal leads being provided at the other end of the encapsulating means and extending in a direction parallel to its axis.

14. Inductor according to claim 1, comprising three windings arranged along the axis of the encapsulating means and inter-connected in T-form, three rings being provided around said encapsulating means and adjustable along said windings to provide a double tuned circuit.

References Cited by the Examiner UNITED STATES PATENTS 2,753,532 7/1956 Ashby et al 336--75 2,885,643 5/1959 Fleming 33696 JOHN F. BURNS, Primary Examiner. 

1. AN INDUCTOR COMPRISING A SUBSTANTIALLY CYLINDRICAL ENCAPSULATING MEANS HAVING OPPOSITE CLOSED ENDS, AT LEAST ONE WINDING LOCATED IN AND EXTENDING AXIALLY OF SAID ENCAPSULATING MEANS, SAID WINDING HAVING TERMINAL LEADS PROJECTING THROUGH AT LEAST ONE SAID CLOSED ENDS OF SAID ENCAPSULATING MEANS, SAID LEADS BEING THE ONLY ELEMENTS WHICH PROJECT FROM THE INTERIOR OF SAID ENCAPSULATING MEANS OUTWARDLY THROUGH AND BEYOND SAID CLOSED ENDS THEREOF, AND AT LEAST ONE METALLIC RING CIRCUMFERENTIALLY SURROUNDING SAID ENCAPSULATING MEANS AND SAID WINDING THEREIN AND BEING AXIALLY MOVABLE ALONG SAID ENCAPSULATNG MEANS BETWEEN SAID ENDS THEREOF, WHEREBY SAID RING WILL ALSO MOVE AXIALLY OF SAID WINDING FOR ADJUSTING THE INDUCTANCE THEREOF, SAID RING CONSTITUTING THE ONLY MEANS BY WHICH SAID INDUCTANCE CAN BE ADJUSTED. 